Re: SQL_NO_CACHE, RESET QUERY CACHE, FLUSH TABLES not working

[Vince Gatto]

It's easy to check if the query cache is being used. Just watch the value of SHOW STATUS LIKE 'Qcache_hits'. If it doesn't change, you're not hitting the cache.

Even with the query cache off, your results are probably normal. MySQL's storage engines implement caching of index and data pages which are frequently used to improve performance. You can't really turn this off (though you can limit the memory they use). Even your operating system will cache frequently accessed disk blocks in memory. All this means that even with the query cache off, your queries should be slowest the first time they are executed, and then speed up after that.

If your goal is to profile your database performance, it's best to find a way to simulate the actual load it will be seeing.